Method of automatically controlling pneumatic or hydraulic elements of instruments and other devices



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METHOD OF AUTOMATICALLY CONTROLLI PNEUMATIC HYDRAULIC ELEMENTS OF INSTRUMENTS OTHER DEV S Filed Feb. 12. 1960 INVENTOR L 4. 2414/44/20 ATTORNEYS United States Patent 3,295,543 METHOD OF AUTOMATICALLY CONTROLLING PNEUMATIC 0R HYDRAULIC ELEMENTS 0F INSTRUMENTS AND OTHER DEVICES Lev Abramovic Zalmanzon, Moscow, U.S.S.R., assiguor to Pneumo-Hydraulic Automatic Control Laboratory of Automatic Control and Telemechanics Institute of the Academy of Sciences of the U.S.S.R., Moscow, U.S.S.R.

Filed Feb. 12, 1960, Ser. No. 10,834 Claims priority, application Great Britain, Dec. 15, 1959, 42,551/59 1 Claim. (Cl. 137-815) This invention relates to a method of control of pneumatic or hydraulic components of instruments and other devices which is free to a great extent from the defects of the heretofore known methods, and is based on the use of the so-called border layer breaking away phenomenon or a gradual change of stream velocity in the so-called flow around wall region in order to control the jet direction.

In accordance with this invention, control of the changing of the jet direction is accomplished by appropriately changing the pressure in the pilot channel or by applying an auxiliary gas or liquid jet to the main jet.

Further objects and advantages of the invention will become apparent from the ensuing description and attached drawings, and in which drawings:

FIG. 1 diagrammatically illustrates one arrangement for utilizing the border, layer breaking away phenomenon by producing pressure in a pilot channel provided in a component of airfoil section,

FIG. 2 diagrammatically illustrates a further arrangement employing an auxiliary gas or liquid jet for controlling the direction of the main jet,

FIGS. 3 and 3a diagrammatically show an aerodynamic oscillator embodying the invention,

FIG. 4 diagrammatically shows a relay arrangement in which the invention is used for obtaining different types of relationship between the output and input pressures or rates of flow, and

FIG. 5 diagrammatically illustrates the use of the invention with a cell or chamber for n egnggigjpg ignals.

When using the border layer brea ing away phenomenon for controlling the position of the main stream or flow in a control system, relatively low pressures and gas or liquid rates of flow .are required. The invention enables the switching or changing of the main jet from one extreme position to another by way of what may be termed snap action.

Referring to FIG. 1, the stream emanating from a feed jet 1 flows around body 2 of air foil section. The body 2 is provided with a pilot channel 3 leading from lower surface 3a to upper surface 3b, and if there is no pressure in such channel the jet streams flows along the path denoted 4. Upon a certain pressure existing in the channel 3, the pressure in the border layer changes, with the border layer breaking away from the upper surface 3b of the body, so that the stream emanating from the jet follows the path indicated 5. Depending upon the profile of the body 2 and the characteristics of the stream, this change of position may occur smoothly or abruptly.

In FIG. 2, the breaking away from the surface of body 2' of the stream discharged from jet 1 is achieved by the action of a stream emanating from an auxiliary jet 7. In this embodiment, parallel control of the border layer of body 2' is possible by changing the pressure in front of the jet 7 and in pilot channel 3', or such channel may be omitted from the body.

With reference to FIGS. 3 and 3a, there is depicted the invention used in connection with an aerodynamic oscil- ICC lator. In this embodiment, pressure fluctuations in a chamber 8 are created as a result of the border layer breaking away and returing to the body 20 with the oscillations occurring as a result in pressure change in the border layer of body 20 when the chamber 8 is filled and emptied. The stream leaving jet 10 after flowing about body 20 enters the opening of chamber 8 (FIG. 3) and the chamber is filled with air. When the pressure in chamber 8 increases, the pressure also changes in the border layer flowing about body 20. At a certain value of this pressure, the stream emanating from jet 10 breaks away from the surface of body 20, and is then directed as shown at A in FIG. 3a. At this moment, chamber 8 begins to empty (FIG. 3a), the pressure being reduced both in chamber 8 and at body 20. At certain values of the pressure that are lower than those at which the stream broke away from the body 20, the stream discharged from jet 10 again follows path B (FIG. 3) and the above cycle is repeated.

Thus, by virtue of the border layer breaking away phenomenon, automatic oscillations are generated, and the arrangement can be used as the drive for vibrating tables, for creating vibrations in instruments, for a component of sine-wave transmitters, and for other purposes.

With reference to FIGURE 4, there is shown a relay arrangement in which, due to the phenomenon above discussed, and due to the control of the border layer in the area or zone in which the stream flows about the body, various embodiments of the characteristics of the pressure change and flow at the outlet are obtained dependent on the pressure and flow at the inlet. More specifically, the fluid stream leaving jet initially flows along the upper surface of the body 200 in the manner indicated at 400. In this situation, the receiving jet or outlet 9 is not under pressure. However, when pressure in pilot channel 300 is increased to a definite value, the flow from jet 100 is broken away from the surface of the body 200 so that such flow is then in the path denoted 500, thereby creating a pressure in the jet 9. In this component, de pending upon the particular profile of the body 200 and the conditions of flow, there may be obtained a relay loop and other characteristics. It should be pointed out that the requirement of purely relay characteristics with an abrupt change of the pressure in the jet 9 accompanying a smooth change of pressure in the pilot channel 300 is important in connection with numerous instruments and devices, particularly pneumatic and hydraulic automatically actuated assemblies.

In connection with FIGURE 5 there is shown an arrangement of the aforementioned phenomena used in connection with' a cell or chamber for memorizing or storing signals. In this embodiment, the jet is denoted 100', the body 200', the pilot channel 300', a cell or chamber 11, a conduit 12 connecting the interior of the chamber 11 with the upper surface of the body 200', and a second control channel or jet located above the body 200'. The control commands are alternately effected and arrested along the channels 300 and 120, and thereafter in chamber or cell 11 until the ensuing signal is given. For example, if the fluid stream discharged from jet 100' flows about the body 200, and there is no control pressure existing in channel 300 the stream is maintained along the upper surface of the body 200' and a zero pressure remains (memorized) within the chamber or cell 11. However, if a pressure is applied to the pilot chamber 300 at a definite pressure value, the fluid stream breaks away from the upper surface of the body 200' and assumes the path denoted P, thereby creating a pressure within the chamber or cell 11. This pressure remains (memorized) if no pressure exists in either the pilot channel 300' or the channel or jet 120.

a point of utilization wherein the flow is used to perform work, the improvement comprising inter-posing an airfoil body between the source and the point of utilization, directing the fluid flow from the source over the airfoil 5 body to effect a border layer at least in the upper surface of the body, and thereafter directing a further fluid flow from an auxiliary source located in proximity to the trail ing edge of the body against the border layer to break away the border layer from the airfoil body and divert in connection with logistical functions as well as other 10 such flow to the point of utilization.

purposes.

It will be appreciated from the foregoing description that by virture of the control of the changing of the flow of a fluid from a fluid source over a body of appropriate contour by virture of applying an auxiliary fluid to the main flow path, the same can be used in connection with the control of pneumatic or hydraulic components of instruments and other assemblies.

This invention is not to be confined to the precise details herein shown and described, but changes or modifications may be made therein so long as such changes or modifications mark no material departure from the spirit and scope of the appended claim.

What is claimed is:

A method of controlling the fluid flow from a source to References Cited by the Examiner UNITED STATES PATENTS 20 M. CARY NELSON, Primary Examiner.

RALPH H. BRAUNER, KARL J. LAVERNE D. GEIGER, Examiners.

F. ENGELTHALER, R. NILSON, S. SCOTT,

Assistant Examiners.

ALBRECHT, 

